Turbine engines often utilize volatile, non-viscous fuels which are very easy to burn. For instance, fuel viscosities even at very low temperatures are typically on the order of 12 centistokes which is believed to be common for the gas turbine industry. However, for some applications, it is necessary to use high density fuels.
By way of example, it may be desirable to use relatively non-volatile, high viscosity JP10 fuel for certain missile applications This fuel, while expensive, nevertheless does provide approximately a twenty percent range increase due primarily to its high density in contrast to low density, volatile, non-viscous fuels such as JP4. But because of the relatively non-volatile nature of JP10, it is usually found to be quite difficult to evaporate for combustion.
Moreover, JP10 is known to have a viscosity up to on the order of approximately 37 centistokes which presents a significant problem. Specifically, this means that fuel atomization by conventional means is difficult if not impossible. As an additional problem, the combustor volume may be very small making acceptable combustion difficult even with volatile, non-viscous fuels.
For this reason, high viscosity fuels such as JP10 present a formidable added problem in applications of the type contemplated herein. This is even more the case since the solution must, for practical reasons, be simple and inexpensive. In this connection, it is known to be desirable to be able to reduce the number and complexity of fuel injectors.
Typically, the objective is to get good mixing of fuel and air not only to assure efficient space utilization with a minimal number of fuel injectors but also to assure optimal combustion. Optimal combustion requires a uniform circumferential air-fuel ratio near stoichiometric. Without good mixing circumferentially, there may be either fuel rich or fuel lean conditions which may well significantly degrade the capability of achieving efficient combustion.
For this reason, and in particular for a small combustor with a minimal available volume, good circumferential mixing of fuel and air is essential.
The present invention is directed to overcoming one or more of the stated problems and achieving the resulting objects.